This invention relates to the treatment of cancer by hyperthermia and more particularly to improvements in the control of whole body or systemic hyperthermia for purposes of retarding the growth of cancel cells.
In my application, Ser. No. 802,033, filed May 31, 1977, now U.S. Pat. No. 4,181,132, there is disclosed a method of effecting whole body or systemic hyperthermia within an individual for anticancer purposes. The method as disclosed involves the establishment and utilization of a sterile extracorporeal flow path for blood having an inlet, an outlet and a temperature control zone therebetween. The extracorporeal flow path is connected with the patient by establishing communication of the inlet of the extracorporeal flow path with the patient's blood stream so that the blood can be withdrawn and supplied to the extracorporeal flow path without adversely affecting the blood circulation in the areas from which the blood is withdrawn. The extracorporeal flow path is also connected with the patient by establishing communication of the outlet of the extracorporeal flow path with the patient's blood stream so that blood flowing from the extracorporeal flow path is returned to the blood stream in such a way as to be distributed systemically. The blood withdrawn from the patient's blood stream is pumped along the extracorporeal flow path through the temperature control zone at a controlled rate of at least approximately one liter per minute for return to the patient's blood stream. The temperature of the blood flowing along the extracorporeal flow path through the temperature control zone is controlled in accordance with the patient's core body temperature. The apparatus for sensing the patient's core temperature disclosed in my prior patent is a rectal probe or an esophageal probe.
Experimental practice of the method as disclosed in my prior patent has indicated that it is highly desirable in the efficacy of the treatment to be able to control the body temperature within 0.1.degree. to 0.2.degree. C. To secure this control there are two aspects which must be present. First, the method utilized to induce the systemic heat must provide such accuracy; and second, the method of sensing the systemic body temperature must likewise be capable of such accuracy. Clearly, to secure maximum effect it is desirable to provide the highest possible heat which is within the tolerance of the patient. This efficacy cannot be achieved by a system capable of inducing such heat if temperature sensing means is not available to determine within the same degree of accuracy just what temperature is being induced. Likewise, the greatest efficacy is not achieved if sufficient accuracy is provided in the temperature sensing of the patient but the means for inducing the systemic temperature is not sufficiently accurate.
Experimental use of the procedures disclosed in my prior patent clearly indicate that the desired accuracy can be obtained by the utilization of an extracorporeal heating circuit in the manner disclosed therein. However, the full efficacy of the procedure has not been consistently realized by the sensing of the patient's body core temperature at the traditional locales of the rectum or esophagus or even the possible third traditional location of the tympanic membrane. For example, when utilizing an esophageal probe there are found to exist three temperature zones depending upon the particular location of the temperature probe in the esophagus rendering the results different depending upon the particular location where use actually takes place. First, where the temperature probe has a position adjacent the right main bronchus, the temperature tends to depend too much on the temperature of the air with which the patient is ventilated. Where the esophageal probe temperature element has a position adjacent the left atrium of the heart, the humidity of the air with which the patient is ventilated can cause somewhat artifically deviant temperature readouts. For example, where the air is too dry, the tendency was to obtain temperature readouts which are slightly too cool. On the other hand, where the air humidity is wet, the temperature sensed appeared to be artifically elevated somewhat. These two locations compared with the remaining locations in the esophagus indicate a difference in the temperature sensed to be between .+-.0.2 to 0.6.degree. C. in utilizing an esophageal probe.
Likewise various inaccuracies could be introduced by the utilization of a rectal probe. For example, the position of the probe could be altered by the normal peristalsis. Moreover, the tip can be encased by stool so as to present an insulation resulting in lower artificial temperature readings. The other traditional locale of the tympanic membrane presents inaccuracies because of the tendency of the accuracy of the readout to be dependent upon actual contact with the very delicate tympanic membrane. Thus, with this location there is a tendency toward light and intermittent contact resulting in artificially lower temperature readings.
It is an object of the present invention to obviate the inaccuracies noted above in sensing patient core body temperature in the traditional locales by utilizing instead a temperature readout of the bladder of the patient. It has been found that a temperature readout in the bladder achieves a consistency of accuracy which is superior to that provided by sensing temperature in the usual three traditional locales because of its central visceral location and also because urine draining from a core organ, the kidney, constantly flows into the bladder. These two factors insure that a thermistor tipped catheter placed into the bladder will enable accurate determination of true body core temperature. In addition urinary catheters are relatively sanitary and comfortable and may readily be retained in position. Inasmuch as a bladder catheter will always be placed in a seriously ill patient, the incorporation of a temperature sensing device such as a thermistor or thermocouple in its tip not only poses no additional discomfort to the patient, but relieves him of the necessity of having another probe inserted into still another orifice.
It is recognized that it has been proposed to provide a thermistor in the tip of a conventional bladder catheter. Such a proposal is contained in an IBM technical disclosure bulletin entitled "Central Body Temperature Apparatus" by E. R. Ellinwood and G. C. Rastelli, Vol. 11, No. 11, dated April of 1969. This disclosure, however, does not suggest the utilization of such a device in systemic hyperthermia nor has the proposed device, to applicant's knowledge, ever been actually produced and utilized in any medical procedure, much less whole body hyperthermia.
It will be understood that whole body or systemic hyperthermia has been induced by others by means other than an extracorporeal heat circuit as described in my prior patent. For example, others have proposed the utilization of hot wax baths or externally applied hot water controlled blankets. As far as applicant is aware none of these methods of inducing systemic hyperthermia has heretofore been controlled by sensing the core body temperature by a bladder temperature sensing probe. Indeed, it may be that the accuracies of induced core body temperature which can be achieved by these procedures is equal to the temperature sensing accuracies that can be achieved by sensing temperature at one or more of the traditional locations. Thus, while the improvements relating to the control of systemic hyperthermia by sensing bladder temperature of the present invention has particular efficacy when utilized to control systemic hyperthermia induced by an extracorporeal blood circuit, such improvement would have equal applicability to systemic hyperthermia induced by any other method capable of achieving accuracies similar to that achieved by the extracorporeal blood circuit method.
Another object of the present invention is the provision of improvements in the apparatus used in inducing hyperthermia through an extracorporeal circuit, such improvements embodying the utilization of a temperature sensing probe in the tip of a bladder catheter.
These and other objects of the present invention will become more apparent during the course of the following detailed description and appended claims.